An access control system is a system that controls an entrance and exit, and is developed on the basis of a conventional door lock. A conventional mechanical door lock is a pure mechanical apparatus. No matter how reasonable a structure is designed and how sturdy a material is, people can always open the lock by various means. For an entrance (of an office building or hotel rooms) visited by many people, key management is troublesome. Once a key is lost or a keeper of the key is changed, the key and its lock need to be changed together. To solve such problems, an electronic magnetic-card lock and an electronic coded lock emerge. Problems of an electronic magnetic-card lock are that information can be easily copied, abrasion between a card and a card reader is great, a fault ratio is high, and a security coefficient is low; and a problem of an electronic coded lock is that a code is vulnerable to leakage and hardly traceable, which leads to a very low security coefficient. In addition, most of such products at that age combine a card reading part (code input) with a control part, and are installed outside a door, so that people can unlock outdoors easily. In recent years, with the development of proximity card technologies and biometric recognition technologies, systems based on various technologies such as a proximity card-type access control system and a fingerprint access control system emerge. However, a proximity card-type access control system is complicated to operate, and a fingerprint access control system has disadvantages such as a fingerprint vulnerable to theft, a client end vulnerable to damage, and a low recognition ratio.
To solve such problems, a light-controlled access control system arises. The light-controlled access control system generally includes a light-controlled client end and an intelligent light-controlled door lock. The light-controlled client end is used to transmit an optical signal that includes unlock code information, and the intelligent light-controlled door lock parses the optical signal after receiving the optical signal; and, if the optical signal includes an unlock code, controls the door lock to open; otherwise, controls the door lock to close. However, an infrared sensing module is added to an existing light-controlled door lock. When somebody approaches the door, a power supply of the intelligent light-controlled door lock is turned on, so as to save electricity. However, the infrared sensing module is instable. If a fault occurs, the intelligent light-controlled door lock cannot be opened or closed. In addition, frequent turn-on and turn-off of the infrared sensing module increase power consumption of the intelligent light-controlled door lock, which is not energy-efficient or environment-friendly.
In addition, in order to save energy and reduce power consumption of electronic products, a body sensing module for controlling a power supply is generally disposed in many existing electronic products. When somebody approaches the product, the body sensing module outputs a high level; and, when nobody approaches the product, the body sensing module outputs a low level, thereby implementing automatic turn-on and turn-off of the electronic products.
For example, an existing pyroelectric far infrared lamp switching module is formed of an infrared sensing controller, a light sensing circuit, a Fresnel lens, a silicon-controlled rectifier trigger circuit capable of having a latency, and the like. An integrated circuit includes a pyroelectric infrared sensor, a two-level operational amplifier, a comparer, a latency timer, zero-crossing detection, and a drive circuit. When a person enters a sensing scope of the switching module, the sensor senses the change of infrared light spectrum of a human body, and the switch turns on a load automatically. When the person stays in the sensing scope, the switch keeps on. Once the person leaves the sensing scope, the switch turns off the load automatically after a little of latency.
Specifically, a human body is a body that emits an infrared ray of a specific wavelength. The body sensing controller can sense proximity of a human body. When a person enters a monitored area, the human body emits a 7˜9 μm infrared ray, which is received by an infrared sensor after being up-converted by the Fresnel lens. The infrared sensor detects the change of infrared heat caused by movement of the human body, and converts the infrared heat into an amount of voltage. After undergoing two-level frequency selection, amplification and comparison, the voltage is input into a control circuit, and the control circuit outputs a zero-crossing pulse to trigger turn-on of a bidirectional silicon-controlled rectifier. In the daytime or when the light is bright, a photosensitive component is in a low-resistance state and triggers no voltage output, the bidirectional silicon-controlled rectifier is cut off and the lamp stay in the off state. At night or when the light is dim, the photosensitive component is in a high-resistance state, and a right of turning on is granted to an input end, which is an output end of the infrared sensing controller. At this time, if a person enters the monitored area, the bidirectional silicon-controlled rectifier is triggered to turn on, and the lamp is powered on; and, when the human body leaves the monitored area, the signal of the silicon-controlled rectifier is triggered to delay for a set time and then the silicon-controlled rectifier is turned off, and the lamp is powered off, which accomplishes automatic turn-off. However, the existing body sensing module has many problems. For example, the load current is too high, the power consumption is too high, and the output voltage is instable, especially when it is applied to security-monitoring products. The security-monitoring products impose high requirements on intelligent control, and a fault occurs once the infrared sensing is insensitive.
In addition, a wireless light communications technology is also called visible light communication, where communication is performed by flashing an LED light source at a high frequency, presence of light indicates 1, and absence of light indicate 0, and a transmission rate can reach a maximum of gigabits per second. In the wireless light communications technology, data is unlikely to be interfered with or captured, and an optical communication device can be easily made and are unlikely to be damaged or degaussed. Therefore, the wireless light communications technology can be used to make a wireless optical encryption key. Compared with microwave technologies, the wireless light communication has abundant spectrum resources, which is incomparable with general microwave communication and wireless communication. In addition, the visible light communication is applicable to any communications protocol, and is suitable for any environment. In terms of security, in contrast to conventional magnetic materials, there is no need to worry about a problem of degaussing, or even to worry about that communication content is intercepted; and optical wireless communication equipment features flexible and convenient installation and layout, and low costs, and is applicable to large-scale popularity and application.
An access control system is a system that controls an entrance and exit, and is developed on the basis of a conventional door lock. A conventional mechanical door lock is a pure mechanical apparatus. No matter how reasonable a structure is designed and how sturdy a material is, people can always open the lock by various means. For an entrance (of an office building or hotel rooms) visited by many people, key management is troublesome. Once a key is lost or a keeper of the key is changed, the key and its lock need to be changed together. To solve such problems, an electronic magnetic-card lock and an electronic coded lock emerge. Problems of an electronic magnetic-card lock are that information can be easily copied, abrasion between a card and a card reader is great, a fault ratio is high, and a security coefficient is low; and a problem of an electronic coded lock is that a code is vulnerable to leakage and hardly traceable, which leads to a very low security coefficient. In addition, most of such products at that age combine a card reading part (code input) with a control part, and are installed outside a door, so that people can unlock outdoors easily. In recent years, with the development of proximity card technologies and biometric recognition technologies, systems based on various technologies such as a proximity card-type access control system and a fingerprint access control system emerge. However, a proximity card-type access control system is complicated to operate, and a fingerprint access control system has disadvantages such as a fingerprint vulnerable to theft, a client end vulnerable to damage, and a low recognition ratio.
To solve the foregoing problems, a light-controlled access control system arises. The light-controlled access control system generally includes an optical signal transmitting apparatus and an optical signal reception control device. The optical signal transmitting apparatus is used to transmit an optical signal that includes unlock code information, and the optical signal reception control device parses the optical signal after receiving the optical signal; and, if the optical signal includes an unlock code, controls the door lock to open; otherwise, controls the door lock to close. The optical signal reception control device uses a dry battery as a power supply, and consumes much electricity. The battery needs to be changed often, which causes inconvenience of use. Overuse of the dry battery also causes environment pollution. Therefore, how to perform energy-saving for the optical signal reception control device becomes an urgent issue to be solved for a light-controlled access control system.
Initially in the coding of an optical signal transmitting apparatus, the number of high levels represents a signal. Each high level lasts about 2 ms. Each group includes at most four high levels. The number of levels in each group represents a 2-bit signal. For example, when the number of high levels in a group of signals is 1, it represents 00; when the number of high levels is 2, it represents a signal 01; when the number of high levels is 3, it represents a signal 10; and, when the number of high levels is 4, it represents a signal 11. A low-level latency is used to distinguish between different groups of signals, where the low-level latency is about 30 ms.
Both the high level and the low level have a specific latency. Therefore, when receiving a signal, the optical signal reception control device may decode the received signal by detecting a high-level and low-level latency on an I/O pin of its control unit. Using a level rising edge as a start of a high level, timing begins when a rising edge is detected. When the high level lasts for more than 1.5 us, the signal is regarded as a valid signal, and the number of high levels is recorded. Using a falling edge as a start of a low level, timing begins when the I/O pin detects the falling edge. When the low level lasts for more than 20 ms, it is deemed an end of a group of signals. When the low level of the I/O pin lasts for more than 75 ms, it is considered that the signal receiving is complete or interrupted, and signal detection resumes.
A decoding method corresponding to the foregoing existing encoding method needs to output and detect relatively many high levels, which leads to signal inability. In addition, the overall sending time and receiving time of the signal are relatively long, and the data transmission is slow.
In addition, a coded lock access control technology is widely used by enterprises. In a coded lock-based access control technology, a code of the coded lock is written into an RFID (Radio Frequency Identification, radio frequency identification) card. When the user makes the RFID card approach a sensing area of the coded lock, the RFID card sends unlock information to the coded lock automatically. After receiving the signal, the coded lock is unlocked if the authentication succeeds.
In the prior art, based on a linear transmission feature of an optical signal, due to stronger confidentiality in contrast to a radio frequency signal, the light communication arises in an access control system. In such access control systems, a decoding unit disposed inside or outside a door receives an optical signal, and, according to the received optical signal, controls unlocking of the door lock disposed inside in the door. However, such door lock has no clock function. Therefore, the user is unable to query the time of opening or closing the door, which reduces user experience.
In addition, an access control controller is used to provide a power supply for an optical signal receiving apparatus and control turn-on and turn-off of an unlocking device. Therefore, the design structure of the entire optical signal receiving apparatus is non-detachable. The optical signal receiving apparatus is generally powered by a battery pack formed of series-connected alkaline batteries. The user needs to change batteries periodically, which leads to environment pollution and brings inconvenience to the user. In addition, the optical signal transmitting apparatus is portable, and the user may carry it along. The optical signal transmitting apparatus is powered by a dry battery. If the dry battery is power-interrupted abruptly, the user is unable to use the optical signal transmitting apparatus to perform the action of opening a door properly.